wtf/RefPtr.h

   1 /*
   2  *  Copyright (C) 2005, 2006, 2007, 2008 Apple Inc. All rights reserved.
   3  *
   4  *  This library is free software; you can redistribute it and/or
   5  *  modify it under the terms of the GNU Library General Public
   6  *  License as published by the Free Software Foundation; either
   7  *  version 2 of the License, or (at your option) any later version.
   8  *
   9  *  This library is distributed in the hope that it will be useful,
  10  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12  *  Library General Public License for more details.
  13  *
  14  *  You should have received a copy of the GNU Library General Public License
  15  *  along with this library; see the file COPYING.LIB.  If not, write to
  16  *  the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  17  *  Boston, MA 02110-1301, USA.
  18  *
  19  */
  20
  21 // RefPtr and PassRefPtr are documented at http://webkit.org/coding/RefPtr.html
  22
  23 #ifndef WTF_RefPtr_h
  24 #define WTF_RefPtr_h
  25
  26 #include <algorithm>
  27 #include "AlwaysInline.h"
  28 #include "FastAllocBase.h"
  29 #include "PassRefPtr.h"
  30
  31 namespace WTF {
  32
  33     enum PlacementNewAdoptType { PlacementNewAdopt };
  34
  35     template <typename T> class PassRefPtr;
  36     template <typename T> class NonNullPassRefPtr;
  37
  38     enum HashTableDeletedValueType { HashTableDeletedValue };
  39
  40     template <typename T> class RefPtr : public FastAllocBase {
  41     public:
  42         RefPtr() : m_ptr(0) { }
  43         RefPtr(T* ptr) : m_ptr(ptr) { refIfNotNull(ptr); }
  44         RefPtr(const RefPtr& o) : m_ptr(o.m_ptr) { T* ptr = m_ptr; refIfNotNull(ptr); }
  45         // see comment in PassRefPtr.h for why this takes const reference
  46         template <typename U> RefPtr(const PassRefPtr<U>&);
  47         template <typename U> RefPtr(const NonNullPassRefPtr<U>&);
  48
  49         // Special constructor for cases where we overwrite an object in place.
  50         RefPtr(PlacementNewAdoptType) { }
  51
  52         // Hash table deleted values, which are only constructed and never copied or destroyed.
  53         RefPtr(HashTableDeletedValueType) : m_ptr(hashTableDeletedValue()) { }
  54         bool isHashTableDeletedValue() const { return m_ptr == hashTableDeletedValue(); }
  55
  56         ~RefPtr() { derefIfNotNull(m_ptr); }
  57
  58         template <typename U> RefPtr(const RefPtr<U>& o) : m_ptr(o.get()) { T* ptr = m_ptr; refIfNotNull(ptr); }
  59
  60         T* get() const { return m_ptr; }
  61
  62         void clear() { derefIfNotNull(m_ptr); m_ptr = 0; }
  63         PassRefPtr<T> release() { PassRefPtr<T> tmp = adoptRef(m_ptr); m_ptr = 0; return tmp; }
  64
  65         T& operator*() const { return *m_ptr; }
  66         ALWAYS_INLINE T* operator->() const { return m_ptr; }
  67
  68         bool operator!() const { return !m_ptr; }
  69
  70         // This conversion operator allows implicit conversion to bool but not to other integer types.
  71         typedef T* (RefPtr::*UnspecifiedBoolType);
  72         operator UnspecifiedBoolType() const { return m_ptr ? &RefPtr::m_ptr : 0; }
  73
  74         RefPtr& operator=(const RefPtr&);
  75         RefPtr& operator=(T*);
  76         RefPtr& operator=(const PassRefPtr<T>&);
  77         RefPtr& operator=(const NonNullPassRefPtr<T>&);
  78         template <typename U> RefPtr& operator=(const RefPtr<U>&);
  79         template <typename U> RefPtr& operator=(const PassRefPtr<U>&);
  80         template <typename U> RefPtr& operator=(const NonNullPassRefPtr<U>&);
  81
  82         void swap(RefPtr&);
  83
  84         static T* hashTableDeletedValue() { return reinterpret_cast<T*>(-1); }
  85
  86     private:
  87         T* m_ptr;
  88     };
  89
  90     template <typename T> template <typename U> inline RefPtr<T>::RefPtr(const PassRefPtr<U>& o)
  91         : m_ptr(o.releaseRef())
  92     {
  93     }
  94
  95     template <typename T> template <typename U> inline RefPtr<T>::RefPtr(const NonNullPassRefPtr<U>& o)
  96         : m_ptr(o.releaseRef())
  97     {
  98     }
  99
 100     template <typename T> inline RefPtr<T>& RefPtr<T>::operator=(const RefPtr<T>& o)
 101     {
 102         T* optr = o.get();
 103         refIfNotNull(optr);
 104         T* ptr = m_ptr;
 105         m_ptr = optr;
 106         derefIfNotNull(ptr);
 107         return *this;
 108     }
 109
 110     template <typename T> template <typename U> inline RefPtr<T>& RefPtr<T>::operator=(const RefPtr<U>& o)
 111     {
 112         T* optr = o.get();
 113         refIfNotNull(optr);
 114         T* ptr = m_ptr;
 115         m_ptr = optr;
 116         derefIfNotNull(ptr);
 117         return *this;
 118     }
 119
 120     template <typename T> inline RefPtr<T>& RefPtr<T>::operator=(T* optr)
 121     {
 122         refIfNotNull(optr);
 123         T* ptr = m_ptr;
 124         m_ptr = optr;
 125         derefIfNotNull(ptr);
 126         return *this;
 127     }
 128
 129     template <typename T> inline RefPtr<T>& RefPtr<T>::operator=(const PassRefPtr<T>& o)
 130     {
 131         T* ptr = m_ptr;
 132         m_ptr = o.releaseRef();
 133         derefIfNotNull(ptr);
 134         return *this;
 135     }
 136
 137     template <typename T> inline RefPtr<T>& RefPtr<T>::operator=(const NonNullPassRefPtr<T>& o)
 138     {
 139         T* ptr = m_ptr;
 140         m_ptr = o.releaseRef();
 141         derefIfNotNull(ptr);
 142         return *this;
 143     }
 144
 145     template <typename T> template <typename U> inline RefPtr<T>& RefPtr<T>::operator=(const PassRefPtr<U>& o)
 146     {
 147         T* ptr = m_ptr;
 148         m_ptr = o.releaseRef();
 149         derefIfNotNull(ptr);
 150         return *this;
 151     }
 152
 153     template <typename T> template <typename U> inline RefPtr<T>& RefPtr<T>::operator=(const NonNullPassRefPtr<U>& o)
 154     {
 155         T* ptr = m_ptr;
 156         m_ptr = o.releaseRef();
 157         derefIfNotNull(ptr);
 158         return *this;
 159     }
 160
 161     template <class T> inline void RefPtr<T>::swap(RefPtr<T>& o)
 162     {
 163         std::swap(m_ptr, o.m_ptr);
 164     }
 165
 166     template <class T> inline void swap(RefPtr<T>& a, RefPtr<T>& b)
 167     {
 168         a.swap(b);
 169     }
 170
 171     template <typename T, typename U> inline bool operator==(const RefPtr<T>& a, const RefPtr<U>& b)
 172     {
 173         return a.get() == b.get();
 174     }
 175
 176     template <typename T, typename U> inline bool operator==(const RefPtr<T>& a, U* b)
 177     {
 178         return a.get() == b;
 179     }
 180
 181     template <typename T, typename U> inline bool operator==(T* a, const RefPtr<U>& b)
 182     {
 183         return a == b.get();
 184     }
 185
 186     template <typename T, typename U> inline bool operator!=(const RefPtr<T>& a, const RefPtr<U>& b)
 187     {
 188         return a.get() != b.get();
 189     }
 190
 191     template <typename T, typename U> inline bool operator!=(const RefPtr<T>& a, U* b)
 192     {
 193         return a.get() != b;
 194     }
 195
 196     template <typename T, typename U> inline bool operator!=(T* a, const RefPtr<U>& b)
 197     {
 198         return a != b.get();
 199     }
 200
 201     template <typename T, typename U> inline RefPtr<T> static_pointer_cast(const RefPtr<U>& p)
 202     {
 203         return RefPtr<T>(static_cast<T*>(p.get()));
 204     }
 205
 206     template <typename T, typename U> inline RefPtr<T> const_pointer_cast(const RefPtr<U>& p)
 207     {
 208         return RefPtr<T>(const_cast<T*>(p.get()));
 209     }
 210
 211     template <typename T> inline T* getPtr(const RefPtr<T>& p)
 212     {
 213         return p.get();
 214     }
 215
 216 } // namespace WTF
 217
 218 using WTF::RefPtr;
 219 using WTF::static_pointer_cast;
 220 using WTF::const_pointer_cast;
 221
 222 #endif // WTF_RefPtr_h